Wastewater reuse is a significant challenge around the world, especially in arid and semi-arid regions. In order to analyse wastewater reuse applications, chemical oxygen demand (COD) is an essential factor for tertiary treat-ment processes. The purpose of this study is to design an approach to evaluate COD removal from low-strength wastewater (COD 70 mg/L) for reuse. This algorithm involves two steps: 1) Activated carbon-activated sludge (AC-AS) and activated sludge-algae (AS-Algae) were investigated, and 2) Optimal conditions were determined through statistical analysis of data. Despite its inherent advantages and robustness, fuzzy logic is a well -recognised alternative algorithm in control applications. As a result of the AC-AS process, an 85% COD removal rate was achieved in 8 hours by combining 0.05 g/L AC and 5 mL/L AS. Under optimal experimental conditions (5 mL/L of AS and 7 mL/L of Algae), a 60% COD removal rate in 7 h was achieved for the AS-Algal process. Both the AC-AS and the AS-Algal systems were found to have 85% and 59% removal efficiencies, respectively. Experimental and predicted values of the AC-AS system and the AS-algal system showed excellent correlation, with a determination coefficient of 0.99 (AC-AS system) and 0.93 (AS-algal system).